Vacuum enveloping component for vacuum-based electronic devices and method of fabrication thereof

ABSTRACT

The apparatus and method of the present invention provide an improved low cost and easy to manufacture vacuum-proof shatter-resistant enveloping component, having superior temperature stability, as well as high temperature and mechanical reliability, that is readily usable with any electronic/thermoelectric device that utilizes enveloped vacuum in the operation thereof. In accordance with various embodiments of the present invention, rather than being made from a single layer glass or a ceramic material, the novel vacuum enveloping component comprises a hollow housing fabricated from a thermo-stable metal alloy, and provided with an inner insulating layer composed of a non-conductive material.

CROSS REFERENCE TO RELATED APPLICATION

The present patent application claims priority from the commonlyassigned co-pending U.S. provisional patent application 61/421,860entitled “IMPROVED VACUUM ENVELOPING COMPONENT FOR VACUUM-BASEDELECTRONIC DEVICES AND METHOD OF FABRICATION THEREOF”, filed Dec. 10,2010.

FIELD OF THE INVENTION

The present invention relates generally to vacuum-based/thermoelectricelectronic devices, and more particularly to high reliabilityvacuum-proof enveloping components usable with various electronicdevices that utilize enveloped vacuum in their operation.

BACKGROUND

Various electronic and electro-thermal devices that utilize vacuum intheir operation (hereinafter “vacuum-based devices”) have been in usefor decades. The most commonly used, and most well-known, vacuum-baseddeices are vacuum tubes (also referred to as electron tubes, and/or asthermionic valves) that are utilized to amplify, switch, otherwisemodify, or create an electrical signal by controlling the movement ofelectrons in a low-pressure space—i.e. the vacuum region surrounded bythe tube's vacuum-enveloping component.

Referring to FIG. 2, a conventional previously known vacuum-basedelectronic/thermo-electric device, is shown as a vacuum-based device 50,having a base/interface component 52 configured for connection to anelectrical interface (e.g., to a socket, etc.), and an active component54, operable to provide the designated electrical signal modificationfunctionality of the device 50, that is surrounded by a vacuum 58sealed-in and enveloped by a vacuum-proof housing 56, which is composedof glass or an equivalent ceramic material. Conventional vacuum-proofhousings, such as housing 56, are currently made from glass or ceramicmaterials primarily due to their relatively high thermal stability andtheir ability to form a fairly reliable seal with the device base.

However, all vacuum-based devices that utilize glass or ceramicmaterials as the vacuum-enveloping components suffer from a number ofsignificant disadvantages:

-   -   (1) glass/ceramic vacuum-enveloping housings are difficult and        expensive to manufacture;    -   (2) glass/ceramic vacuum-enveloping housings are notoriously        fragile and are prone to catastrophic failure that makes the        device unusable.        -   (a) For example, a crack in the glass envelope housing will            allow air into the device and destroy it. Cracks may result            from stress in the glass, bent pins (of the device base), or            from impacts to device.        -   (b) Moreover; device bases (e.g., sockets) must allow for            thermal expansion, to prevent stress in the glass housing at            the pins. Stress may accumulate if a metal shield or other            object presses on the glass envelope housing and causes            differential heating of the glass.        -   (c) Glass envelope housing may also be damaged by            high-voltage arcing in the device;    -   (3) one of the greatest challenges in design and fabrication of        conventional vacuum-based devices, is the proper selection of        materials for the metal bases (e.g. sockets, pins, etc.) and for        glass/ceramic vacuum-enveloping housings, that have matching or        very similar thermo-expansion factors to prevent the        glass/ceramic material from cracking around device pins or at        the interface with the device base). While there are “workable”        material pairings known in the field, the temperature ranges        thereof are very narrow (e.g., about 200 degrees Celsius for        glass). This problem also limits options for design of new or        customized vacuum-based devices.

BRIEF DESCRIPTION OF THE DRAWING

In the drawings, wherein like reference characters denote correspondingor similar elements throughout the various figures:

FIG. 1 depicts an exemplary embodiment of the inventive improvedvacuum-proof enveloping component implemented in an exemplaryvacuum-based electronic/thermo-electric device; and

FIG. 2 shows a conventional previously known vacuum-basedelectronic/thermo-electric device utilizing a glass or ceramicvacuum-enveloping component.

DETAILED DESCRIPTION

The apparatus and method of the present invention address the variousflaws and drawbacks of previously known vacuum-basedelectronic/thermo-electric devices (such as conventional vacuum tubes,etc.). The inventive apparatus and method advantageously provide animproved low cost and easy to manufacture vacuum-proof shatter-resistantenveloping component, having superior temperature stability, as well ashigh temperature and mechanical reliability, that is readily usable withany electronic/thermoelectric device that utilizes enveloped vacuum inthe operation thereof. In accordance with various embodiments of thepresent invention, rather than being made from a single layer glass or aceramic material, the novel vacuum enveloping component comprises ahollow housing fabricated from a thermo-stable metal alloy (such as analuminum-based alloy—e.g., duraluminum), and provided with an innerinsulating layer composed of a non-conductive material (deposited on theinner surface of the housing via any appropriate process, such as byapplication of a physical or electrostatic coating, physical vapordeposition, micro-arc oxidation, etc.).

FIG. 1 depicts an exemplary embodiment of the inventive improvedvacuum-proof enveloping component implemented in an exemplaryvacuum-based electronic/thermo-electric device 10. The vacuum-baseddevice 10 includes a base/interface component 12 which may be composedof any desired material and which includes various interface elements(e.g., pins, etc.), and also includes at least one active component 14(at least a portion of which may optionally extend into, and be disposedin, the base/interface 12) that is operable to provide device 10 primaryfunctionality—e.g., amplification, switching, or other modification ofan electronic signal, etc. Advantageously, the device 10 also includes anovel vacuum-enveloping hollow housing 16 that is mounted on, orotherwise securely connected to, the base/interface 12, in a manner thatseals in a vacuum 18 disposed around the active component 14.

Preferably, the novel housing 16 comprises an outer housing layer 16 afabricated from a thermo-stable metal alloy (such as an aluminum-basedalloy—e.g., duraluminum), and also comprises an inner insulating layer16 b composed of a non-conductive material (deposited on the innersurface of the outer housing layer 16 a via any appropriate process,such as by application of a physical or electrostatic coating, physicalvapor deposition, micro-arc oxidation, etc.).

Advantageously the housing 16 of the present invention readily solvesone of the most significant challenges in both the design and infabrication of vacuum-based devices—the need to carefully match thethermo-expansion factors of materials selected for the metal bases (e.g.sockets, pins, etc.) of the device, and of materials for theglass/ceramic vacuum-enveloping housings, and the design limitations ofhaving to work in the very narrow range of thermal expansion values ofglass/ceramic materials. The inventive housing 16 does not suffer fromthe above thermo-expansion matching limitations, and furthermore byvirtue of its metal-based composition has much higher thermalconductivity.

Thus, while there have been shown and described and pointed outfundamental novel features of the inventive apparatus as applied topreferred embodiments thereof, it will be understood that variousomissions and substitutions and changes in the form and details of thedevices and methods illustrated, and in their operation, may be made bythose skilled in the art without departing from the spirit of theinvention. For example, it is expressly intended that all combinationsof those elements and/or method steps which perform substantially thesame function in substantially the same way to achieve the same resultsare within the scope of the invention. It is the intention, therefore,to be limited only as indicated by the scope of the claims appendedhereto.

1. A method for fabricating a vacuum enveloping component for use withvacuum-based electronic and thermo-electric devices, comprising thesteps of: (a) fabricating a hollow housing from a material comprising atleast one metal of at least a predetermined desired degree of thermaland mechanical stability, said hollow housing being sized and configuredto provide vacuum-enveloping functionality to a predeterminedvacuum-based device, and comprising an interior surface region, and (b)depositing an insulating material layer over at least a substantialportion of said inner surface region.